/*
 * R : A Computer Language for Statistical Data Analysis
 * Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
 * Copyright (C) 1997--2008  The R Development Core Team
 * Copyright (C) 2003, 2004  The R Foundation
 * Copyright (C) 2010 bedatadriven
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.renjin.primitives.special;

import org.renjin.eval.Context;
import org.renjin.eval.EvalException;
import org.renjin.sexp.Environment;
import org.renjin.sexp.FunctionCall;
import org.renjin.sexp.Null;
import org.renjin.sexp.PairList;
import org.renjin.sexp.SEXP;
import org.renjin.sexp.SpecialFunction;

public class OnExitFunction extends SpecialFunction {

  public OnExitFunction() {
    super("on.exit");
  }

  @Override
  public SEXP apply(Context context, Environment rho, FunctionCall call, PairList args) {
    EvalException.check(call.getArguments().length() <= 2,
        "invalid number of arguments");

    if(call.getArguments().length() == 0) {
      // remove existing on exit functions
      context.clearOnExits();
      context.setInvisibleFlag();
      return Null.INSTANCE;

    } else {

      SEXP value = call.getArgument(0);
      boolean add = false;
      if(call.getArguments().length() == 2) {
        add = context.evaluate(call.getArgument(1), rho).asReal() != 0;
      }

      if(add) {
        context.addOnExit(value);
      } else {
        context.setOnExit(value);
      }
      context.setInvisibleFlag();
      return Null.INSTANCE;
    }
  }
}
